British Pat. No. 1,424,703 discloses a weft yarn guide for a jet loom which comprises: a base portion connected to a sley; a pair of guide members forked from the base portion so as to form a weft inserting opening, and; a plurality of fluid blowing holes disposed on the circumference of the pair of guide members around the weft inserting opening. In this weft yarn guide, an air flow is supplied through an air passage formed within both the base portion and the pair of guide members. When this weft yarn guide is actually used, there is a defect in that the intensities of the auxiliary air jets blown through the fluid blowing holes are not uniform therebetween, and accordingly, the weft yarn cannot be carried properly because the weft yarn is pushed upwards.
To eliminate the defect in the above-mentioned prior art apparatus, another type of weft yarn guide has been proposed, wherein fluid blowing holes are formed only on the upper surfaces of the forked guides members, so that air jets which may push up the weft yarn are omitted. However, in this weft yarn guide, no consideration is given to the design of the air passage formed within the base portion and the pair of guide members, especially at the junction of the base portion and the pair of guide members, and accordingly, air flow fed from the base portion impinges upon the upper inner wall of the air passage at the junction and causes turbulences, and as a result, the intensities of the auxiliary air jets blown through the fluid blowing holes cannot be uniform.